Method and device for the plasma treatment of workpieces

ABSTRACT

The invention relates to a method and a device which are used for the plasma treatment of work pieces. Said work piece is inserted into an at least partially evacuatable chamber of a treatment station ( 3 ) and the work piece is positioned inside the treatment station of retaining elements. At least one operating agent is at least partially impinged upon by a transporting device ( 44 ) which is displaced together with the treatment station on a closed and rotating transport path.

The invention concerns a method for the plasma treatment of workpieces,wherein the workpiece is inserted in a plasma chamber of a treatmentstation, which can be at least partially evacuated, and wherein theworkpiece is positioned inside the treatment station by a mountingelement.

The invention also concerns a device for the plasma treatment ofworkpieces, which has at least one plasma chamber, which can beevacuated, for holding the workpieces, in which the plasma chamber islocated in the area of a treatment station, and in which the plasmachamber is bounded by a chamber floor, a chamber lid and a lateralchamber wall and has at least one mounting element for positioning theworkpiece.

Processes and devices of this type are used, for example, to applysurface coatings to plastics. In particular, processes and devices ofthis type are also already known for coating inner or outer surfaces ofcontainers used for holding liquids. Devices for plasma sterilizationare also well known.

PCT-WO 95/22413 describes a plasma chamber for coating the inner surfaceof PET bottles. The bottles to be coated are raised into a plasmachamber by a movable base and connected at their mouths to an adapter.The inside of the bottles can be evacuated through the adapter. A hollowlance for supplying process gas is also inserted into the inside of thebottles through the adapter. Microwaves are used to ignite the plasma.

The same publication also describes the arrangement of a plurality ofplasma chambers on a rotating wheel. This helps achieve a highproduction rate of bottles per unit time.

EP-OS 10 10 773 describes a feeding device for evacuating the inside ofa bottle and supplying it with process gas. PCT-WO 01/31680 describes aplasma chamber into which the bottles are introduced by a movable lidthat has first been connected with the mouths of the bottles.

PCT-WO 00/58631 also already describes the arrangement of plasmastations on a rotating wheel and the assignment of groups of vacuumpumps and plasma stations for an arrangement of this type to helpprovide favorable evacuation of the chambers and the interiors of thebottles. It also mentions the coating of several containers in a commonplasma station or a common cavity.

Another system for coating the inside surfaces of bottles is describedin PCT-WO 99/17334. This document describes especially an arrangement ofa microwave generator above the plasma chamber and means for evacuatingthe plasma chamber and supplying it with operating agents through thefloor of the plasma chamber.

In most of the previously known methods, silicon oxide coatings, whichhave the general chemical formula SiO_(x) and are produced by theplasma, are used to improve the barrier properties of the thermoplasticmaterial. In addition, barrier layers produced in this way can alsocontain carbon, hydrogen, and nitrogen components. Barrier layers ofthis type prevent oxygen from penetrating the bottled liquids andprevent the escape of carbon dioxide from liquids that contain CO₂.

The previously known methods and devices are still not sufficientlysuitable for use in a mass-production process, in which it is necessaryto achieve both a low coating cost per workpiece and a high productionrate.

Therefore, the objective of the present invention is to develop a methodof the aforementioned type in such a way that the operating agents canbe effectively supplied to the treatment station, and a compactconstruction, short process idle times and a high degree of reliabilitycan be achieved at the same time.

In accordance with the invention, this objective is achieved in such away that at least one operating agent is admitted at least partially bya delivery device, which is moved together with the treatment station ona closed and rotating transport path.

A further objective of the present invention is to design a device ofthe aforementioned type that allows operating agents to be supplied tothe plasma chamber and to achieve a compact construction at the sametime.

In accordance with the invention, this objective is achieved byarranging the plasma chamber and at least one delivery device for anoperating agent on a rotating support device.

The common arrangement of the plasma chamber and the delivery device forthe operating agents on a rotating support device makes it possible tosupply the operating agents in the necessary form in the immediatevicinity of the plasma chamber. This helps achieve a compact design,and, in addition, very short connecting lines can be used. Furthermore,flow losses along long lines are eliminated by the spatially densearrangement of the delivery device and the plasma chamber relative toeach other, so that short process idle times are achieved.

The physical conditions necessary for the plasma treatment can bequickly reached if the delivery device produces a negative pressure.

Rapid evacuation can also be achieved if at least two different negativepressures are produced by at least two delivery devices.

A good compromise between a low weight to be transported and thesupplying of the operating agents with little or no time delay isobtained if a preconditioned operating agent is supplied for at leastone delivery device by at least one preliminary stage.

Stationary and moving components can be connected by conveying theoperating agents to the vicinity of the delivery device through arevolving turret.

Advantageous positioning of the center of mass can be achieved if thedelivery device conveys the operating agents from a height level of thedelivery device to a higher level of the plasma station.

To connect a plurality of plasma stations, it is proposed that at leasttwo plasma stations be connected with at least one common deliverydevice by a distributor.

Operating agents can be supplied through short connecting lines if atleast one operating agent is distributed by at least one distributor ata height level of a chamber base of the plasma station.

In particular, it is also possible for the operating agents to besupplied by the distributor in the direction of the plasma stationsthrough connecting lines that are straight and run radially outward fromthe distributor.

Compact distribution of different operating agents is assisted byconveying at least two operating agents to the plasma stations atdifferent distribution levels.

When rotating support devices are used, it is found to be especiallyadvantageous if the delivery devices are arranged in the area of thesupport device in such a way that an essentially balanced weightdistribution is provided.

A combination of a favorable weight distribution and good accessibilitycan be achieved by positioning delivery devices and distributioncabinets for electrical connections alternately along the circumferenceof the support device.

A system that is very stable and at the same time supports exactlyreproducible performance of all process steps can be achieved bypositioning the delivery device together with the plasma station on arotating plasma wheel as the support device.

A typical application consists in the treatment of a workpiece made of athermoplastic material.

The method is intended especially for treating the interior of theworkpiece.

A large area of application consists in the treatment of containers asthe workpieces.

In this regard, it is intended especially that a beverage bottle betreated as the workpiece.

A high production rate with a high degree of reliability and highproduct quality can be achieved by transferring the one or more plasmastations from an input position to an output position by a rotatingplasma wheel.

An increase in production capacity with only a slight increase inequipment expense can be achieved if one plasma station comprisesseveral cavities.

An embodiment that can withstand large mechanical loads is obtained ifthe delivery devices are conveyed by a plasma wheel with an annularshape.

A typical application is defined as the performance of a plasma coatingas the plasma treatment.

It is intended especially that the plasma treatment be carried out withthe use of a low-pressure plasma.

In the case of the coating of plastic workpieces, it has been found tobe advantageous to carry out a plasma polymerization.

Good surface adhesion is promoted if at least some of the substancesdeposited by the plasma are organic substances.

Especially advantageous practical properties of workpieces to be usedfor packaging foods can be obtained if at least some of the substancesdeposited by the plasma are inorganic substances.

In the treatment of packages, it is intended especially that a substancethat improves the barrier properties of the workpiece be deposited bythe plasma.

To promote high practical quality, it is proposed that an adhesionpromoter be additionally deposited on a surface of the workpiece toimprove the adhesion of the substance.

High productivity can be promoted by simultaneously treating at leasttwo workpieces in a common cavity.

Another area of application consists in the performance of a plasmasterilization as the plasma treatment.

The method can also be used to carry out a surface activation of theworkpiece as the plasma treatment.

A design that is compact and can withstand large loads can be achievedby providing the plasma wheel with a supporting ring that has anessentially C-shaped vertical section.

An especially low position of the center of mass is achieved byarranging the delivery device on a base leg of the supporting ring.

A modular basic design with good accessibility of the individualfunctional components is provided by arranging the plasma stations on aterminal leg of the supporting ring.

Specific embodiments of the invention are schematically illustrated inthe drawings.

FIG. 1 shows a schematic diagram of a plurality of plasma chambers,which are arranged on a rotating plasma wheel, which is coupled withinput and output wheels.

FIG. 2 shows an arrangement similar to FIG. 1, in which each plasmastation is equipped with two plasma chambers.

FIG. 3 shows a perspective view of a plasma wheel with a plurality ofplasma chambers.

FIG. 4 shows a perspective view of a plasma station with one cavity.

FIG. 5 shows a front elevation of the device in FIG. 4 with the plasmachamber closed.

FIG. 6 shows a cross section along cross-sectional line VI-VI in FIG. 5.

FIG. 7 shows the same view as in FIG. 5 but with the plasma chamberopen.

FIG. 8 shows a vertical section along cross-sectional line VIII-VIII inFIG. 7.

FIG. 9 shows an enlarged view of the plasma chamber with a bottle to becoated in accordance with FIG. 6.

FIG. 10 shows a perspective view of a support device, which has pumpsfor operating agents arranged on a rotating plasma wheel as well asplasma stations, which have two plasma chambers each and are likewisearranged on the plasma wheel.

FIG. 11 shows another, partially transparent, view of a plasma wheelsimilar to FIG. 10 without the distribution box.

FIG. 12 shows the plasma wheel of FIG. 11 in a partially assembledstate.

FIG. 13 shows the plasma wheel of FIG. 11 with only one plasma stationinstalled.

FIG. 14 shows the plasma wheel of FIG. 13 in a different perspectiveview and shows external delivery devices for operating agents.

FIG. 15 shows a schematic representation of another plasma wheel, inwhich delivery devices for operating agents are arranged in a verticallyupper area.

FIG. 16 shows a partial view of another design of a plasma wheel, whichhas an overhead suspension and in which delivery devices for operatingagents are positioned vertically above the plasma stations.

The view in FIG. 1 shows a plasma module (1), which is provided with arotating plasma wheel (2). A plurality of plasma stations (3) isarranged along the circumference of the plasma wheel (2). The plasmastations (3) are provided with cavities (4) and plasma chambers (17) forholding the workpieces (5) that are to be treated.

The workpieces to be treated (5) are fed to the plasma module (1) in theregion of an input (6) and further conveyed by an isolating wheel (7) toa transfer wheel (8), which is equipped with positionable support arms(9). The support arms (9) are mounted in such a way that they can beswiveled relative to a base (10) of the transfer wheel (8), so that thespacing of the workpieces (5) relative to one another can be changed. Inthis way, the workpieces (5) are transferred from the transfer wheel (8)to an input wheel (11) with increased spacing of the workpieces (5)relative to one another compared to the isolating wheel (7). The inputwheel (11) transfers the workpieces (5) to be treated to the plasmawheel (2). After the treatment has been carried out, the treatedworkpieces (5) are removed from the area of the plasma wheel (2) by anoutput wheel (12) and transferred to the area of an output line (13).

In the embodiment shown in FIG. 2, each plasma station (3) is equippedwith two cavities (4) and plasma chambers (17). This makes it possibleto treat two workpieces (5) at a time. In this connection, it isbasically possible to design the cavities (4) completely separate, butit is also basically possible to separate only sections of a commoncavity space from each other in such a way that optimum coating of allworkpieces (5) is ensured. In particular, it is intended here that thecavity sections be separated from each other at least by separatemicrowave couplings.

FIG. 3 shows a perspective view of a plasma module (1) with a partiallyassembled plasma wheel (2). The plasma stations (3) are installed on asupporting ring (14), which is designed as part of a revolving joint andis mounted in the area of a machine base (15). Each plasma station (3)has a station frame (16), which supports plasma chambers (17). Theplasma chambers (17) have cylindrical chamber walls (18) and microwavegenerators (19).

A rotary distributor (20), by which the plasma stations (3) are suppliedwith operating agents and power, is located in the center of the plasmawheel (2). Especially ring conduits (21) can be used for distribution ofthe operating agents.

The workpieces (5) to be treated are shown below the cylindrical chamberwalls (18). For the sake of simplicity, lower parts of the plasmachambers (17) are not shown in the drawing.

FIG. 4 shows a perspective view of a plasma station (3). The drawingshows that the station frame (16) is provided with guide rods (23), onwhich a slide (24) for mounting the cylindrical chamber wall (18) isguided. FIG. 4 shows the slide (24) with the chamber wall (18) in itsraised position, so that the workpiece (5) is exposed.

The microwave generator (19) is located in the upper region of theplasma station (3). The microwave generator (19) is connected by a guide(25) and an adapter (26) to a coupling duct (27), which opens into theplasma chamber (19). Basically, the microwave generator (19) can beinstalled directly in the vicinity of the chamber lid (31) or coupledwith the chamber lid (31) at a predetermined distance from the chamberlid (31) via a spacing element and thus installed in a largersurrounding area of the chamber lid (31). The adapter (26) acts as atransition element, and the coupling duct (27) is designed as a coaxialconductor. A quartz glass window is installed in the area of the openingof the coupling duct (27) into the chamber lid (31). The guide (25) isdesigned as a waveguide.

The workpiece (5) is positioned in the area of a sealing element (28),which is located in the vicinity of the chamber floor (29). The chamberfloor (29) is formed as part of a chamber base (30). To facilitateadjustment, it is possible to mount the chamber base (30) in the area ofthe guide rods (23). An alternative is to mount the chamber base (30)directly on the station frame (16). In an arrangement of this type, itis also possible, for example, to design the guide rods (23) in twoparts in the vertical direction.

FIG. 5 shows a front elevation of the plasma station (3) of FIG. 3 withthe plasma chamber (17) closed. The slide (24) with the cylindricalchamber wall (18) is lowered here relative to the position in FIG. 4, sothat the chamber wall (18) is moved against the chamber floor (29). Inthis position, the plasma coating can be carried out.

FIG. 6 shows a vertical sectional view of the arrangement in FIG. 5. Itis especially apparent that the coupling duct (27) opens into a chamberlid (31), which has a laterally projecting flange (32). A seal (33),which is acted upon by an inner flange (34) of the chamber wall (18), islocated in the area of the flange (32). When the chamber wall (18) islowered, the chamber wall (18) becomes sealed relative to the chamberlid (31). Another seal (35) is located in the lower region of thechamber wall (18) to ensure sealing relative to the chamber floor (29).

In the position shown in FIG. 6, the chamber wall (18) encloses thecavity (4), so that both the interior of the cavity (4) and the interiorof the workpiece (5) can be evacuated. To assist with the introductionof process gas, a hollow lance (36) is mounted in the area of thechamber base (30) and can be moved into the interior of the workpiece(5). To allow positioning of the lance (36), the lance is supported by alance slide (37), which can be positioned along the guide rods (23). Aprocess gas channel (38) runs inside the lance slide (37). In its raisedposition shown in FIG. 6, the process gas channel (38) is coupled with agas connection (39) of the chamber base (30). This arrangementeliminates hose-like connecting elements on the lance slide (37).

FIGS. 7 and 8 show the arrangement of FIGS. 5 and 6 with the chamberwall (18) in its raised position. When the chamber wall (18) ispositioned in this way, the treated workpiece (5) can be removed fromthe area of the plasma station (3) without any problems, and a newworkpiece (5) to be treated can be inserted. Alternatively to thepositioning of the chamber wall (18) that is shown in the drawing, withthe plasma chamber (17) in an open state produced by upward movement ofthe chamber wall (18), it is also possible to perform the openingoperation by moving a structurally modified, sleeve-like chamber wallvertically downward.

In the illustrated embodiment, the coupling duct (27) has a cylindricalshape and is arranged essentially coaxially with the chamber wall (18).

FIG. 9 shows a vertical section in accordance with FIG. 6 in an enlargedpartial view of the area around the chamber wall (18). Especiallyevident in the drawing are the overlapping of the inner flange (34) ofthe chamber wall (18) over the flange (32) of the chamber lid (31) andthe mounting of the workpiece (5) by the mounting element (28).Furthermore, the drawing shows that the lance (36) passes through ahollow space (40) in the mounting element (28).

FIG. 10 shows a plasma module (1) that is modified compared to the viewin FIG. 3. The plasma wheel (2) is designed here for the rotatingtransport of plasma stations (3), each of which has two plasma chambers(17). Each of the plasma stations (3) has two microwave generators (19),two guides (25), and two adapters (26), which introduce the microwavesinto each of the associated plasma chambers (17) through coupling ducts(27) to ignite the plasma. The supporting ring (14) of the plasma wheel(2) has a C-shaped profile in a vertical cross section, with a base leg(41), a spacing leg (42), and a terminal leg (43). The spacing leg (42)runs essentially vertically, and the base leg (41) and the terminal leg(43) are arranged essentially horizontally. The base leg (41) and theterminal leg (43) extend radially outward from the spacing leg (42).

The plasma stations (3) are arranged vertically above the terminal leg(42). In the embodiment shown in FIG. 10, delivery devices (44) for anoperating agent are installed on the base leg (41). The operating agentis supplied to the plasma stations (3). In the illustrated embodiment,the delivery device (44) is realized as a vacuum pump. In addition tothe delivery devices (44), distribution cabinets (45) for the electricpower supply of the plasma stations (3) are installed on the base leg(41). In this regard, the delivery devices (44) and the distributioncabinets (45) are installed inside the holding space made available bythe C-shaped vertical section of the supporting ring (14).

During rotation of the plasma wheel (2), the arrangement described abovecauses the delivery devices (44) and the distribution cabinets (45) torotate together with the plasma stations (3), and there is no relativemovement between these assemblies. Suitable connecting lines can thus berealized in a simple way.

FIG. 11 shows a plasma module (1) that is slightly modified from thedrawing in FIG. 10 in a different view and with a partially alteredrepresentation of the individual parts. The microwave generators (19)are positioned differently from the drawing in FIG. 10. In addition, thechamber bases (30) are drawn in between the lance slides (37) and theplasma chambers (17) in FIG. 11. Especially control valves for supplyingthe plasma chambers (17) with operating agents can be installed in thearea of the chamber bases (30).

The distribution cabinets (45) are not shown in FIG. 11, so that it ispossible to look into the center of the plasma wheel (2). The drawingshows that a revolving turret (46) is installed approximately at theheight level of the delivery devices (44). The revolving turret (46)serves to connect the delivery devices (44) with external deliverydevices (47). When the plasma stations (3) are operated with threedifferent negative pressures, namely, a first negative pressure, asecond negative pressure that is lower than the first negative pressure,and a process negative pressure, the revolving turret (46) is realizedas a revolving three-way vacuum inlet. Connection of the revolvingturret (46) to the external delivery devices (47) can be accomplished ina simple way by connecting pipes (48), which run partially below themachine base (15). For this purpose, the machine base (15) has supportelements (49), which provide installation space below the machine base(15) by providing vertical spacing between the machine base (15) and amounting surface.

The revolving turret (46) is connected by lines (50) with the associateddelivery devices (44). In the drawing in FIG. 11, the spacing leg (42)is shown partially transparent, so that the path of the lines (50) canbe seen.

FIG. 12 shows the arrangement of FIG. 11 in a partially assembled state.In particular, it shows that a distributor (51) is arranged at a heightlevel similar to the height level of the plasma chambers (17). In theillustrated embodiment, the distributor (51) is realized as a three-waydistributor. To this end, the distributor (51) has three distributionsegments arranged vertically one above the other. The distributionsegments are each connected with the plasma chambers (17) by connectinglines (52). In the illustrated embodiment, two operating agents are eachsupplied to the distributor (51) by a delivery device (44). To this end,the delivery devices (44) are connected with the distributor (51) byconnecting lines (53). An additional operating agent is supplied to thedistributor (51) directly from the revolving turret (46) by an ascendingline (54).

For further explanation, FIG. 13 shows the arrangement according to FIG.12 with only one plasma station illustrated. In particular, the drawingshows the arrangement of the three segments of the ventilator (51)vertically one above the other and the path of the connecting lines (48)between the distributor (51) and the chamber base (30). The connectinglines (52) are guided directly to valves arranged in the area of thechamber base (30). In particular, FIG. 13 also illustrates that thedistributor (51) is supported by the lines (52, 53) in the illustratedembodiment. This provides good accessibility. However, it is alsopossible to use additional supporting elements.

FIG. 14 shows the arrangement according to FIG. 13 in a differentperspective view and with six external delivery devices (47) assigned toit. In this connection, two external delivery devices (47) are assignedto each vacuum level. In the illustrated embodiment, the deliverydevices (47) for the first vacuum level provide a negative pressure onthe order of 30-50 mbars. This negative pressure is made available tothe plasma stations (3) in the illustrated embodiment without additionalconveyance devices (44) on the plasma wheel (2) directly through therevolving turret (46). The negative pressures for the other externaldelivery devices (47) are preset as a function of the given processrequirements. In particular, a pressure range on the order of 1-10 mbarsis intended. Rotary sliding-vane vacuum pumps, Roots vacuum pumps, ordesigns combined from these types of pumps can be used as deliverydevices (44, 47). In a preferred embodiment, Roots vacuum pumps are usedas the delivery devices (44) installed on the plasma wheel (2), androtary sliding-vane vacuum pumps are used as the external deliverydevices (47).

To avoid unnecessarily long connecting pipes (48), it is especiallyintended that the external delivery devices (47) be positioned adjacentto the plasma module (1). To this end, it is possible, for example, touse a special preliminary stage module. The required external deliverydevices (47) can be arranged inside such a preliminary stage module,which can be equipped with standardized connections for connection tothe plasma module (1). This greatly simplifies both assembly and thesubsequent start-up operation.

In the embodiment shown in FIG. 14, the two external delivery devices(47) for the first vacuum level are connected in parallel relative toeach other. On the other hand, the other external delivery devices (47)for the second vacuum level, which operates at a lower pressure levelthan the first vacuum level, and for the third vacuum level formaintaining the negative pressure while the treatment is being carriedout, are connected in series. This takes into account the fact that theprimary concern in the production of the relatively higher negativepressure is to evacuate a relatively large volume, whereas in the caseof the other two vacuum levels at lower pressure than the first vacuumlevel, the primary concern is to attain the desired low level, which isassisted by the series connection.

FIG. 15 shows an embodiment in which the delivery devices (44) areinstalled at a higher level than the plasma stations (3). Although thisresults in a higher center of gravity of the plasma wheel (2), it alsoprovides very good accessibility to the delivery devices (44) duringboth installation and subsequent service work. In an embodiment of thistype, connection with the external delivery devices (44) is preferablyaccomplished by connecting pipes (48), which initially run above theplasma module (1) and are then connected with the external deliverydevices (47) by vertical lines (55). The installation of the deliverydevices (44) above the plasma stations (3) makes it possible to arrangethe plasma stations (3) at a relatively low level, so that theworkpieces (5) to be treated can also be inserted and removed at arelatively low height level.

FIG. 16 shows another embodiment of the plasma module (1). In this case,the plasma wheel (2) is suspended in a support frame (56). In contrastto the previously explained embodiments, a pivot bearing (57) of theplasma wheel (2) is thus located vertically above the plasma wheel (2)rather than vertically below the plasma wheel (2). The design of theplasma station (3) can remain basically the same as in the otherembodiments. FIG. 16 shows only a partial view of the plasma station (3)without the chamber base (30) and without the lance slide (37) andassociated parts.

In an embodiment as shown in FIG. 16, with the use of delivery devices(44) installed on the plasma wheel (2), a relatively low arrangement ofthe plasma chambers (17) can also be retained. In the specificembodiment illustrated here, three delivery devices (44) are positionedon the plasma wheel (2). Relative to a pivot bearing (57) supported bythe support frame (56), the plasma stations (3) are installed below thepivot bearing (57), and the delivery devices (44) are installed abovethe pivot bearing (57). As a result of this arrangement of the pivotbearing (57) at a high level, a high degree of structural stability canbe provided, despite the arrangement of the delivery devices (44) at ahigh level.

A typical treatment operation is explained below for the example of acoating operation and is carried out in such a way that the workpiece(5) is first conveyed to the plasma wheel (2) by means of the inputwheel (11), and that the workpiece (5) is inserted into the plasmastation (3) with the sleeve-like chamber wall (18) in its raisedposition. After completion of the insertion operation, the chamber wall(18) is lowered into its sealed position, and then both the cavity (4)and the interior of the workpiece (5) are evacuated, simultaneously atfirst.

After sufficient evacuation of the interior of the cavity (4), the lance(36) is inserted into the interior of the workpiece (5), andpartitioning of the interior of the workpiece (5) from the interior ofthe cavity (4) is carried out by moving the sealing element (28). It isalso possible to start moving the lance (36) into the workpiece (5)synchronously with the start of evacuation of the interior of thecavity. The pressure in the interior of the workpiece (5) is thenfurther reduced. Moreover, it is also possible to carry out thepositioning movement of the lance (36) at least partly at the same timeas the positioning of the chamber wall (18). After a sufficiently deepnegative pressure has been achieved, process gas is introduced into theinterior of the workpiece (5), and the plasma is ignited by means of themicrowave generator (19). In particular, it is intended that the plasmabe used to deposit both an adhesion promoter on the inner surface of theworkpiece (5) and the actual barrier layer consisting of silicon oxides.The adhesion promoter can be applied, for example, in a two-stageprocess before the application of the barrier layer. However, it is alsoconceivable to use a continuous process to apply at least a portion ofthe barrier layer even while at least a portion of the adhesion promoteris being applied.

The interior of the plasma chamber (17) and the interior of theworkpiece (5) are first evacuated together to a pressure level of about20 mbars to 50 mbars. The pressure in the interior of the workpiece (5)is then further reduced to about 0.1 mbar. A negative pressure of about0.3 mbar is maintained during the performance of the treatmentoperation.

After a coating operation has been completed, the lance (36) iswithdrawn from the interior of the workpiece (5), and the plasma chamber(17) and the interior of the workpiece (5) are ventilated. After ambientpressure has been reached inside the cavity (4), the chamber wall (18)is raised again to allow the coated workpiece (5) to be removed and anew workpiece (5) to be inserted for coating. To allow lateralpositioning of the workpiece (5), at least part of the sealing element(28) is moved back into the chamber base (3).

Alternatively to the coating of the internal surface of workpieces (5)that was explained above, it is also possible to coat the externalsurface or to carry out sterilization or surface activation.

The chamber wall (18), the sealing element (28), and/or the lance (36)can be positioned by means of various types of drive equipment. Inprinciple, it is possible to use pneumatic drives and/or electricdrives, especially in the form of linear drives. In particular, however,it is also possible to realize a cam mechanism to help achieve exactcoordination of motion with the rotation of the plasma wheel (2). Forexample, the cam mechanism can be designed in such a way that controlcams, along which cam followers are driven, are arranged along thecircumference of the plasma wheel (2). The cam followers are coupledwith the given components that are to be positioned.

1. Device for inner coating containers with a barrier layer, which hasat least one plasma chamber, which can be evacuated, for holding thecontainers, in which the plasma chamber is located in the area of atreatment station, and in which the plasma chamber is bounded by achamber floor, a chamber lid, and a lateral chamber wall and has atleast one mounting element for positioning the container, wherein theplasma chamber (17) is disposed on a rotating plasma wheel and at leastone delivery device (44) for an operating agent are arranged on arotating support device, wherein the rotating support device is situatedbeneath the rotating plasma wheel, wherein the delivery device (44) is apump configured to produce a negative pressure and connected to thetreatment station, wherein the pump is at a lower height level than theplasma chamber, wherein the treatment station is also connected to aprocess gas supply that provides the process gas needed to produce thebarrier layer.
 2. Device in accordance with claim 1, wherein at leasttwo delivery devices (44) for producing different negative pressures areinstalled on the support device.
 3. Device in accordance with claim 1,wherein at least one of the delivery devices (44) is connected to atleast one external delivery device (47) for supplying a preconditionedoperating agent.
 4. Device in accordance with claim 3, wherein at leasttwo external delivery devices (47) are connected in parallel relative toeach other.
 5. Device in accordance with claim 3, wherein at least twoexternal delivery devices (47) are connected in series relative to eachother.
 6. Device in accordance with claim 1, wherein the delivery device(44) is connected to an external source of the operating agent by arevolving turret (46).
 7. Device in accordance with claim 1, wherein thedelivery device (44) is connected to at least two plasma stations (3) bya distributor (51).
 8. Device in accordance with claim 7, wherein thedistributor (51) is arranged at the same height level as a chamber base(30) of the plasma station (3).
 9. Device in accordance with claim 7,wherein the distributor (51) is connected with a chamber base (30) byconnecting lines (52) that run essentially radially outward.
 10. Devicein accordance with claim 9, wherein the distributor (51) has differentdistribution levels for the distribution of different operating agents.11. Device in accordance with claim 1, wherein at least two deliverydevices (44) are arranged on the support device in an essentiallybalanced way.
 12. Device in accordance with claim 11, wherein deliverydevices (44) and distribution cabinets (45) for electrical connectionsare alternately arranged along the circumference of the support device.13. Device in accordance with claim 1, wherein the delivery device (44)is installed on a support device designed as a plasma wheel (2). 14.Device in accordance with claim 13, wherein the plasma wheel (2) isdesigned as a wheel ring.
 15. Device in accordance with claim 14,wherein the plasma wheel (2) is provided with a supporting ring (14).16. Device in accordance with claim 15, wherein the delivery device (44)is installed on a base leg (41) of the supporting ring (14).
 17. Devicein accordance with claim 15, wherein the treatment stations areinstalled on a terminal leg (43) of a supporting ring (14).
 18. Devicein accordance with claim 1, wherein the plasma station (3) is designedfor coating a container (5) made of a thermoplastic material.
 19. Devicein accordance with claim 1, wherein the plasma station (3) is designedfor coating a container (5) shaped in the form of a beverage bottle. 20.Device in accordance with claim 1, wherein several cavities (4) arearranged in the area of the treatment station.
 21. Device in accordancewith claim 1, wherein a chamber wall (18) provided for supplying atleast two cavities (4) is arranged in such a way that it can bepositioned.